Starting switch for fluorescent lamps



Sehfi R. E. TAFFANY ET AL STARTING SWITCH FOR FLUORESCENT LAMPS Filed Oct. 4, 1947 .ffiventorgn Raymond ET iFFany,

Frank -J.Knajcik, by WfiflLf Their Attorr'wey Patented Sept. 6, 1949f STARTING SWITCH FOR FLUORESCENT LAMPS Raymond E. Tiffany and Frank J. Krajcik,

Bridgeport, Conn, assignors to General Electric Company, a corporation 01' New York Application October 4, 1947, Serial No. 777,954

1 Claim. 1

The present invention relates to a startin switch for fluorescent lamps of the hot cathode type.

It is the object of our invention to provide a manually operated fluorescent lamp starting switch having only a few simple parts which can be manufactured at a low cost and yet provide reliable long life operation.

Our invention will best be understood from the following description taken in connection with the accompanying drawing in which Fig. 1 is an elevation of the switch mechanism with the case and cover in partial section; Fig. 2 is a section taken along the line 2-2 in Fig. 1 and showing the under side of the switch mechanism and Fig. 3 is a diagrammatic representation of the switch as connected in a lamp starting circuit.

Referring to Figs. 1 and 2, our switch comprises a casing l which is preferably molded of insulating material in a single piece having a cavity 2 open at the top and adapted to be closed by a cover plate 3. Both of the thickened end walls of the casing have portions of their inner surfaces cut-away to provide separated ledges 4 at the left end and ledges 5 at the right end as viewed in Fig. 1. Two screw and one rivet receiving holes extend vertically into each end wall. Stationary contacts 6 and I are mounted beneath terminal elements 8 and 9 respectively, the latter being supported on the ledges 4 and held in place by screws Ill and H threaded into the outermost holes in the ledges 4. The contact elementsfi and I are inside the recess 2 while the opposite ends of the terminal elements 8 and 9 project outside of the casing through suitable openings l2 in the casing and wall. Connections to the stationary contacts of the switch can thus readily be made to the terminal elements 8 and 9 outside the switch casing.

The opposite ledges 5 support the movable contacts. These consist of contact elements l3 and I4 secured to elongated, conducting, spring members l5 and I6 respectively, which are mounted on the ledges 5 and secured thereto by screws l1 and i8 threaded into the outermost holes in the ledges 5. Contacts I3 and I4 are positioned within the cavity 2 so as to be adapted to engage the contacts 8 and 1 respectively. The opposite ends of the spring contact members l5 and I6 project out of the casing through openings [9 in the casing end wall to provide terminals for the connection of the movable contacts into a lamp starting circuit. The center portions of the spring members l5 and 16 are lanced to provide arcuately shaped upwardly extending metal projections forming cam followers 15a and [6a adapted to ride against cams operated by a manually operable trigger member 20. The cover plate 3 of the switch is held in place on the casing l by means of the rivets 3| and 32 or equivalent fastening means which pass through the central holes in the thickened end walls of the casing. The cover plate has an opening through which the handle 24 of trigger member 20 projects.

The movable contact actuating trigger member 20, which is preferably made in a single piece of molded insulating material, is provided with two axially aligned stub shafts 22. These shafts are journaled in bearings formed by depressions in the side walls of the casing I. The actuating member 20 has a central-portion 21 which is disc like and substantially circular in shape except for a downwardly extending projection 23 and an upwardly extending projection 24 forming an operating handle for the member 20. On both sides of the central portion 2| there are formed contact operating cam portions 25 and 26. The cams 25 and 26 are basically circular segments with centers on the axis of shafts 22. The bottom surfaces of both cams have, however, three depressions or cam steps arcuate in shape to receive the cam followers l5a and 16a to provide three definite positions for trigger 20. However,

only certain of these steps are major steps deep enough to permit closing of the contacts.

Cam 25 has a sing e major depression or step 21. When the cam follower l6a rises into the step 21, movable contact l3 engages stationary contact 6. Cam 25, on the other hand, has two major steps 28 and 29, the latter being aligned with step 21 of the cam 25. When the cam follower I5a enters either of the steps 28 or 29, movable contact l4 engages fixed contact I. In all other positions of the cams the respective contacts are open.

The trigger member 20 has bearing against its side a positioning spring 30, one end of which is secured to the casing l by means of the rivet 3|. The shape of the central portion of trigger member 20, as previously mentioned, is circular except for the projection 23. Thus when the handle 24 is thrown to the left, as viewed in Figures 1 and 3, the spring 30 exerts no rotational force on the trigger member, nor does it exert any such force in the intermediate position of the handle 24, that is, the position shown in the drawing. When, however, the handle 24 is thrown to the right, the projection 23 engages spring 30 so that the spring will tend to return the trigger member to the position shown in the drawing.

The manner of operation of the switch will be readily apparent from Figure 3 which shows the switch connected in circuit with a fluorescent lamp 33 having hot cathodes 34a and b. One terminal of each of the cathodes is connected to the extremities 01 a ballast '35 having a center tap 36 which is connected to movable contact M. The corresponding fixed contact I is connected to one side of the line, represented by a conventional contact plug 31. The other side of the line is connected to the ballast and cathode filament 34a whose opposite terminal is connected to stationary contact 6. The remaining terminal of cathode filament 34b is connected to the movable contact i3. A condenser 38 is connected in shunt across contact 6 and I3.

The switch is shown in the lamp operating position. If the handle 24 be thrown to the left, both sets of contacts will be open. To start the lamp, the handle 24 is thrown all the way to the right. In this position, cam follower Hia will move into step 21 of the cam 25 closing contacts 6 and i3, and cam follower I5a will move into step 28 of the cam 26 closing contacts I and M. The two lamp filaments 34a and 341) are thereby energized. When the handle 24 is let go, spring pressing against projection 23 will rotate the trigger member 20 to the central or operating position, as shown in the drawing. Contacts 6 and i3 are thereby opened while contacts 'i and i4 remain closed. Inasmuch as a portion of the ballast circuit has been interrupted by the opening of contacts 6 and IS, a high voltage kick will be produced starting the arc in the lamp 33.

What we claim as new and desire to secure by Letters Patent of the United States is:

A starting switch for a fluorescent lamp comprising a casing having walls defining a recess, a trigger member journalled in said casing, said trigger member comprising an integral molded element having three adjacent disc-like cam portions all of basically arcuate edge surface contour, the center of said cam portions having a 4 projection extending thereirom and the side cam portions each having three successive depressions in their surfaces correspondingly spaced in an axial direction, two stationary contact members mounted at one end 01 said recess, two movable contact members mounted at the other side 01 said recess and extending across the same beneath said side cam portions and carrying movable contacts adapted to cooperate with said stationary contacts, said movable contact members having spring portions carrying projections adapted to bear against and to engage said depressions in said side cam portions for providing three switch positions and for the operation of said contacts, one pair of said depressions corresponding to one switch position and being relatively shallow for limiting the motion of the movable contacts whereby in that switch position said contacts are open, the central depression in only one of said side cam portions being relatively deep whereby in the central switch position one of said movable contacts engages its corresponding stationary contact and the remaining pair or depressions in both cam portions being relatively deep whereby in the third switch position both pairs of contacts are closed, and leaf spring means mounted in the casing and adapted to bear tangentially against said central portion and in the third switch position only to bear against said central portion projection for exerting a rotational force on said trigger member tending to rotate the same into said central switch position.

RAYMOND E. TIFFANY. FRANK J. KRAJCIK.

REFERENCES orrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,203,224 Kimball June 7, 1940 2,352,936 Bryant July 4, 1944 2,408,165 Harrawood Sept. 24, 1946 

